Add filter on categories and tasks to volunteer admin
Add filter on categories and tasks to volunteer admin

cateee/fosdem-volunteers,cateee/fosdem-volunteers,cateee/fosdem-volunteers,FOSDEM/volunteers,cateee/fosdem-volunteers,jrial/fosdem-volunteers,jrial/fosdem-volunteers,FOSDEM/volunteers,FOSDEM/volunteers,FOSDEM/volunteers,jrial/fosdem-volunteers,jrial/fosdem-volunteers